东北地区玉米生育期干旱分布特征及其成因分析

Analysis of Distributional Characteristics and Primary Causes of Maize Drought in Northeast China

利用1961-2008年东北地区124个气象站的日气象数据,定义了表征玉米不同生育时期干旱强度的水分亏缺指标,并对干旱时空分布及其年际变化特征进行分析。结果表明,东北地区玉米生长季内干旱呈明显的季节性和区域性。从发育阶段看,苗期干旱频率较高,随生育期后移干旱频率明显减少,以轻旱为主要发生类型,春秋降水量少是发生干旱的主要原因;从空间分布看,干旱呈东北向西南逐渐增加的趋势,区域性较明显,总体上为辽宁西北部、吉林西部至黑龙江西南部发生频率较高。各年代之间比较,20世纪60-80年代干旱频率呈减少趋势,90年代初期呈增加趋势,90年代中期以后增加趋势明显,特别是2000-2004年维持在一个较高水平。各年代干旱发生频率均表现为苗期>拔节-孕穗期>灌浆-成熟期>抽雄-开花期。苗期和拔节-孕穗期干旱发生频率均以60年代较高,以轻度干旱为主要发生类型;抽雄-开花期干旱发生频率以90年代较高,以轻度干旱为主要发生类型;灌浆-成熟期轻、中、重度干旱发生频率均以2001-2008年为高。由此可见,研究区干旱发生频率呈增高趋势,特别是玉米产量形成关键期的干旱频率呈增加趋势,对玉米生产的不利影响增大。研究结果对了解东北地区玉米不同发育期干旱分布特征及其成因,并采取相应对策措施具有积极意义。

Based on the observational data collected from 124 meteorological stations in Northeast China from 1961 to 2008,water deficit indices were defined for maize in different growth stage,and then spatial and temporal distributional characteristics of drought were analyzed on the basis of inter-annual variation features.The results indicated that the occurrences of drought showed distinct seasonal and regional features.In the view of growth stage,drought occurred with high frequency at the seedling stage and the frequency decreased evidently at afterwards growth stages.Slight drought happened in higher frequency than moderate and severe drought.The main cause of drought was the seasonal distribution characteristics of precipitation.In the view of spatial scale,the occurrence frequency of drought for different degrees reduced gradually from west to east.The most frequent areas of drought were northwestern of Liaoning province,western of Jilin province and southwest of Heilongjiang province,respectively.For interdecadal variation characteristics,drought frequency decreased from 1960s to 1980s,increased slightly in the early of 1990s and increased apparently after the middle of 1990s,especially increased dramatically from 2000 to 2004.In view of different growth stage in the years,the trend of drought frequency was seedling stage＆gt;jointing-booting stage＆gt; filling-maturation stage＆gt;tasseling-flowering stage.The most frequent water stress was slight drought for seedling stage during 1960s and 1990s,slight drought stress occurred frequently at tasseling and flowering stage during 1990s.All kinds of drought happened frequently at kernel filling to mature stage from 2001-2008.Thus it can be seen that the occurrence frequency of drought has increased in this area over the past several decades,especially in the critical period of yield formation of maize,and has dramatically adverse effect on maize yield.The results show positive significance to better understand the causes and distribution characteristics of drought for different growth stages of maize in Northeast China and then it will be beneficial to take appropriate measures.